Study of complexes of a tryptophan-free mutant of E. coli trp aporepressor with tryptophan analogues using optically detected magnetic resonance (ODMR).
Phosphorescence and optically detected magnetic resonance (ODMR) spectra of tryptophan (W) and several of its analogues (4-, 5-, 6-methyltryptophan (MeW); 4-, 5-, 6-fluorotryptophan (FW); 5-bromotryptophan) are compared with those of complexes formed with the W-free trp aporepressor from Escherichia coli (W19,99F). W19,99F binds W and each analogue except 4-FW with an estimated KD < or = 30 microM; triplet state spectroscopic and kinetic effects that accompany binding at the corepressor site are reported. ODMR data for the MeW isomers are presented for the first time. No binding of 7-azaW is observed, in agreement with the low affinity found by previous workers.
Ozarowski
A
A
Department of Chemistry, University of California, Davis 95616, USA.
Wu
J Q
JQ
Maki
A H
AH
D001059:Apoproteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D004926:Escherichia coli / Q000737:chemistry*; D007700:Kinetics; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins
D001059:Apoproteins; D001426:Bacterial Proteins; D012097:Repressor Proteins; D014364:Tryptophan; C027190:TRPR protein, E coli; D029968:Escherichia coli Proteins